数字博物馆中的图像盲水印技术*

针对数字博物馆中图像数量大、类型多的特点,提出一种适用于多种类型图像的盲水印算法。该算法将用户ID作为水印信息,从而实现对图像的操作跟踪。水印嵌入时,首先将水印信息转换成ASCII码形式,并对其进行交织和BCH编码以提高抗突发和随机错误的能力,然后根据图像类型取得嵌入水印的载体,再对该载体语义丰富的位置进行分块DCT变换,最后通过修改子块DCT系数间关系嵌入水印。水印检测时,以嵌入过程的逆过程抽取水印信息,并计算其与所有用户ID的相似度来获得初始嵌入的ID。实验表明,该算法能抵抗一般的信号处理操作和特定条件下的几何变换。     

基于DCT变换的彩色图像水印盲提取算法

为利用Q R码的快速识别、高容量和高容错等特性,实现彩色图像的水印盲提取,提出基于DC T变换的彩色图像水印嵌入和提取算法。对彩色图像的3个通道进行8%8分块,取DC系数中M SB位作为水印嵌入地址,通过余数调整的方法实现水印的嵌入。提取水印时,通过对水印嵌入位的余数判定,对3个通道的结果进行投票处理,提取出水印信息,提取过程不需要原图像和原水印图像,是一种盲提取算法。通过实验验证了该方法的鲁棒性和透明性,计算复杂度较低,相对于很多变换域水印算法有明显优势。     

基于ROI的组合域数字水印算法

提出一种基于ROI的组合域数字水印算法。将水印信号中感兴趣部分提取作为重要信息,混沌加密后嵌入载体图像的DCT域。将原始水印信号经过Arnold变换,嵌入含水印图像空域的非LSB位。水印提取时不需要原始载体图像。     

基于正交向量组的多水印算法研究

在一组正交向量中,向量与自己的内标积为1,向量之间的内标积为0,利用这一特性,对多个水印信息分别进行扩频调制。将调制后的信息线性组合后嵌入到载体中,使得多个水印在嵌入和提取时互不影响;多个水印可以分多次嵌入到载体图像中,先后嵌入的水印是彼此无关的,从而解决多水印算法中嵌入的水印信息之问相互干扰的问题,为数字图像产品的多著作权的保护提供了一种有效手段。实验表明,该算法对于噪声、旋转、缩放和JPEG压缩等常见攻击有良好的鲁棒性。     

一种基于混沌动力系统同步原理的非对称水印

提出了一种基于混沌动力系统同步原理的非对称数字水印构造方法.将二值水印图像转化为二进制数字信号,控制混沌驱动系统两路交替输出信号,形成载有水印信息的混沌信号,并将其作为水印信号嵌入载体图像.水印提取过程中将提取出的水印信号送入混沌响应子系统,根据响应子系统的输出信号与水印信号的相关性来恢复水印图像.在水印嵌入及提取过程中使用不同的混沌系统模型、参数及状态变量初值,实现了非对称数字水印系统的构造.     

基于局部相关匹配的小波变换图像水印方法*

现有局部感兴趣区域的水印嵌入方法在选取感兴趣区域时未考虑水印信号能与载体图像局部相似的特性,本文提出一种基于局部相关匹配的小波变换图像水印方法。该方法利用Arnold变换对水印图像加密,采用相位相关法选取合适的水印嵌入区域,并根据图像纹理的差异在小波的高频和低频系数上分别嵌入水印信息。水印检测时,在嵌入水印的区域提取出多个水印信息,将多个水印信息的加权平均作为检测水印。实验结果表明,该方法嵌入水印的不可见性及抗噪声和压缩的性能较好。     

一种基于倒谱变换的自同步音频水印算法

本文提出了一种基于倒谱变换的自同步数字音频水印算法。算法对音频载体分段后,将同步码嵌入到时域上,将水印信息嵌入到变换域上。水印的提取不需要原始音频信号,是一种盲水印算法。实验结果表明,嵌入后的水印不仅具有很好的不可感知性,而且对添加噪声、重新采样、低通滤波、重新量化和剪切攻击也具有很好的稳健性。     

MPEG-4码流中的数字水印

基于视频码流内嵌入数字水印典型系统H&G算法的基础,提出了在MPEG-4码流中嵌入数字水印的一种新算法。该算法在MPEG-4视频流中,根据局部图像特性调整水印嵌入的局部强度以达到水印鲁棒性的最大化和视频质量影响的最小化;同时构造了具有纠错功能的水印信息并且在水印信息提取过程中采用了信号合并技术得到了较高的正确率。计算机试验表明此算法与嵌入水印前的原视频图像相比,嵌入水印后的视频图像信噪比损失很小.并证明信号合并技术具有很好的提取水印能力。     

结合提升小波和QR码的盲水印实现

提出了一种结合提升小波和QR码的盲水印实现。嵌入水印时,首先对需要版权保护的图像进行提升小波变换,然后对水印图像进行QR码编码处理,再对得到的QR码图像进行混沌处理以提高算法的安全性,最后将经过QR码编码、混沌处理的水印信息通过元胞自动机处理嵌入到原始图像的提升小波逼近子图中。水印提取时,对经过上述处理后的图像应用元胞自动机、混沌系统、QR码解码得到原始水印信息。仿真结果表明,该实现方法具有较高的鲁棒性,能够抵抗剪切、修改、噪声等攻击。该实现方法能够广泛应用于版权保护领域,具有一定的实用价值。     

基于DCT与双随机矩阵的图像数字水印方案

在水印的嵌入与检测过程中用到了3个密钥，双随机矩阵和嵌入尺度作为秘密钥保证了水印嵌入的安全性，DCT系数矩阵之和则作为公开钥用于水印信息的部分认证．文中算法实现了将图像作为水印信息隐藏到载体图像中；把水印信息的每一点都通过某种方式嵌入到载体图像的多个点上；使得攻击者在不知道秘密钥的情况下无法删除或改变水印信息．通过实验对嵌入和检测结果进行了比较和分析，表明该算法具有很好的稳健性．     

结合多级小波系数加权均值和量化的可公开敏感水印

传统水印通常对水印嵌入后掩体视觉质量较为关注,而对水印嵌入环节的安全性较为忽视,一些算法尽管提供了水印加密环节,但位置固定,导致嵌入水印易受攻击,而基于参数化小波的水印敏感性在实际中难以应用。针对以上问题,提出一种结合多级小波系数加权均值和量化的可公开敏感水印。在该算法中,首先将掩体图像的消息摘要算法5(MD5)值、用户密钥和初始参数与Logistic映射绑定,用于对水印加密和嵌入环节的多级小波系数进行随机选择;然后通过联合图像专家组(JPEG)压缩的各级小波系数绝对变化量的算术平均值来估算小波系数权重,调整小波系数加权均值以嵌入水印;最后通过孤立黑点滤除策略来提高水印提取质量。理论和实验表明,所提方法具有较好的明文敏感性和密钥敏感性,嵌入水印后图像峰值信噪比(PSNR)可达到45 dB,即使公开水印嵌入环节,嵌入的水印也难以篡改和提取,同时依然对图像剪裁、白噪声、JPEG压缩、覆盖和涂鸦等常规图像攻击具有鲁棒性。     

平衡多小波视觉密码零水印算法

传统零水印算法构造的水印通常是没有实际意义的二值序列,致使版权辨别不够直观快捷。借鉴视觉密码原理,结合平衡多小波、奇异值分解等技术,提出平衡多小波视觉密码零水印算法。将客户水印作为零水印嵌入到版权图像中,对版权图像进行平衡多小波变换得到实际载体;根据实际载体图像进行块奇异值分解并计算平衡因子得到差值矩阵,由差值矩阵生成过渡矩阵;将过渡矩阵结合2×2视觉秘密图份算法生成图像特征信息;结合图像特征信息和客户水印信息产生零水印。实验结果表明,该算法具有良好的安全性和鲁棒性,是一种可靠的图像版权认证零水印算法。     

基于小波能双重自恢复的音频数字水印算法

本文设计了一种在音频信息中加入双重图像作为数字水印,这些水印经过多种攻击能相互自恢复的算法。此算法实现了将双重图像作为数字水印嵌入到WAV音频载体中的过程,在实现过程中通过对载体进行3层小波分解,将数字水印的信息嵌入到第三层小波解的低频区,即CA3中,并对双重数字水印分别设置密钥,建立起两者间稳定的映射关系,能较好地以完成自恢复的功能。     

基于动态间隔压缩的鲁棒网络流水印算法

针对基于间隔质心的流水印缺乏纠错能力且难以抵御多流攻击的问题,提出一种基于动态间隔压缩的鲁棒网络流水印算法。该算法在基于间隔质心流水印基础上利用编解码技术增强其纠错能力,将携带同一水印信息的网络流量采用动态间隔压缩的方式调制为多种模式以抵御多流攻击。同时在检测端对水印进行分层检测,减少检测端计算资源浪费。实验结果表明,当检测阈值设为0.8时,误报率低于5%,且水印检测率可高于原始间隔质心方法10%左右,合并多条水印数据流后也无明显静默间隔。可见该算法具有良好的鲁棒性和隐蔽性,能够有效提高网络流水印的可用性。     

基于Turbo码的数字水印方案

提出一种基于Turbo码数字水印方案。该算法既对水印图像进行编码,又对载体图像进行编码。编码数据在经过较低信噪比的信道传输后,由解码算法能同时恢复水印和载体图像。不同于传统数字水印方法,本文方案要求接收用户掌握Turbo解码密钥,方能正确恢复水印和载体图像。本文给出了方案设计流图,然后给出仿真实验结果,仿真结果表明算法在通信中保护水印和载体图像方面是可行的。     

Robust multi bit and high quality audio watermarking using pseudo-random sequences

A robust multi bit and high quality audio watermarking technique in time domain is proposed in this paper. Watermarking is a technique used to label digital media by hiding copyright or other information into the underlying data. The watermark must be imperceptible and undetectable by the user and should be robust to various types of distortion. To enhance the robustness and taper-resistance of the embedded watermark, in this paper a multi bit technique is employed. Instead of embedding one bit into an audio frame, multiple bits can be embedded into each audio sub-frame. For attackers, since they do not know the parameters, this significantly reduces the possibility of unauthorized bit detection and removal of watermark. In real-time watermarking applications, robustness is not the only factor that plays an important role. The other factor that plays a very an important role is computational complexity. In general, audio file is transmitted in compressed form. Real-time watermark embedding must take into account this compressed form, because first decompressing the data, adding a watermark and then recompressing the data is computationally too demanding. In this paper, we propose robust and low complexity audio watermarking algorithm. To evaluate the performance of the proposed audio watermarking algorithm, subjective and objective quality tests including bit error rate (BER) and signal-to-noise ratio (SNR) were conducted. Compared to traditional one bit embedding algorithm, the proposed algorithm gives highly recovery rate after attack by commonly used audio data manipulations, such as low pass filtering, requantization, resampling, and MP3 compression.     

Scene-based fingerprinting method for traitor tracing

In this paper, scene-based fingerprinting method for traitor tracing is proposed which is computationally less complex and handles large user group, say 10¹¹ users while requiring few frames to embed the watermark. The proposed method uses QR code as a watermark due to its three main features: (1) inherent templates, (2) noise resiliency, and (3) compact size. The proposed method creates the QR code watermark on-the-fly which is then segmented and embedded parallely inside the scenes of video using the watermarking key. The features of QR code, segmentation, and watermarking key not only help the proposed method in supporting a large user group but also make it computationally fast. Further, synchronization issues may arise due to addition and deletion of scenes. To avoid such scenarios, the proposed method matches the inherent templates present in QR code with the templates present in the segments of the extracted watermark. Experimental results show that the proposed method is computationally efficient and is robust against attacks such as collusion, scene dropping, scene addition, and other common signal processing attacks.     

一种带纠错编码的小波零树基图像水印算法

提出了一种新颖的数字水印纠错编码方案。通过对二值水印图像进行精心设计，引入纠错编码机制，并将其应用于传统的小波零树(EZW)算法中。实验结果表明，在相同的水印嵌入强度和攻击强度条件下，通过引入纠错编码机制，可以显著提高水印在抗JEPG压缩、抗几何攻击、抗中值滤波、抗噪声干扰等方面的鲁棒性。     

A low-cost method for reliable ownership identification of medical images using SVM and Lagrange duality

Prevention of false positive and false negative errors is a major challenge for ownership identification and proof of ownership applications using digital image watermarking. Such errors are more critical with sensitive data, such as electronic patient records (EPRs) in medical image watermarking. A false positive error is a watermark detection error, which means that a watermark is detected in a media where there is no watermark. In contrast, a false negative error is an inability of the watermark detector to detect an embedded watermark in a watermarked image. These errors make ownership assessments unreliable, and the incorrect ownership identification of a patient’s record could result in failure of the correct diagnostics and treatments. To address this type of problem, a low-cost technique based on a support vector machine (SVM) and Lagrange duality was proposed to achieve reliable approximations for ownership identification in medical image watermarking without requiring the correction of attacked watermarked images. In this technique, the results of the ownership evaluation are categorized into two independent classes, namely watermark-detected and watermark-not-detected, and higher geometric margins between these classes are associated with higher reliability. To address additional situations with false positive and false negative errors, four different situations, including watermarked, unwatermarked, attacked watermarked and attacked unwatermarked images, were investigated. Experiments were conducted on duo-ISB-bit-plane (BiISB) watermarking using the histogram intersection (HI) technique as a testing platform under JPEG2000 and JPEG image compression attacks and using two groups of images: standard image processing images and X-ray medical images. The experimental investigations revealed that the HI technique guarantees that the rightful owner can be reliably identified even after severe attacks and in the face of context similarities between the watermark and the embedding pixels of the host image.